Onkológia 1/2014

The relationship between genetics and histologic pattern oligodendroglioma

Introduction: Loss of heterozygosity on the short arm of the 1. chromosome and on the long arm of the 19. chromosome (1p/19q LOH) is a genetic hallmark of oligodendrogliomas and significant prognostic and predictive marker. The aim of the study was to assess the possibility to predict 1p/19q LOH status by the means of the classic histomorphologic features of oligodendroglial tumours. Patients and methods: In the period from May 2007 to May 2010 were prospectively enrolled patients whose histology was evaluated in the Cytopathos Ltd. and examined 1p/19q LOH status. Histologic diagnoses were based on WHO 2007 criteria. 8 histologic features were semiquantitatively assessed. Bivariant statistics was applied and output was monitored by simple logistic regression. Afterwards multivariable logistic model was constructed from the variables with significant contribution to the discriminating power of the model. Cut-off of the logistic model was set 0.5 and sensitivity, specificity, positive and negative predictive values were calculated for that according to pertinent confidence intervals. Results: 70 patients with tumourous brain lesions were included in the study, 41 men and 29 women. Average was 43.5 years (range 3-84 years). All histological parameters were significant except for cellularity and microcystic change. Optimal logistic model composed from gender and three histologic features was able to predict presence of 1p/19q LOH with sensitivity 89.3% and specificity 88.1%. Positive predictive value of the model is 83.3%, negative predictive value is 92.5%. Conclusion: On our set of patients we confirmed strong correlation between 1p/19q and classic oligodendroglial histomorphology. Our model does not replace genetic examination, but if it is unavailable, it can be used for prediction of the 1p/19q LOH status.

Keywords: oligodendroglial tumours, 1p/19q LOH, prognostic and predictive markers.